Such mouthpieces which may e.g. be intended for vacuum cleaning are usually provided with a flexible joint that connects the suction sole to the suction pipe of the vacuum cleaner, said connecting joint being so designed that the vacuum cleaner mouthpiece may freely occupy different angles relative to the vacuum cleaner mouthpiece. In this manner the suction sole of the vacuum cleaner mouthpiece may easily sweep a surface irrespective of the orientation of the suction pipe of the suction cleaner.
Owing to the construction of the flexible joint, the known vacuum cleaner mouthpieces of this type allow the mouthpiece to be turned in the surface plane during use by rotation of the vacuum cleaner's suction pipe about its longitudinal axis. On the one hand, it is desired in this connection that it is possible to turn the mouthpiece slightly in order to access inaccessible places, and on the other hand that the mouthpiece may be turned with a small effort on the part of the user, whereby an impact on the vacuum cleaner mouthpiece, e.g. when bumping into furniture and the like during use, will entail a relatively small moment of force on the suction pipe.
Therefore the known joints are so arranged that a given angle change in the position of the vacuum cleaner suction pipe entails a relatively smaller angle change of the mouthpiece in the surface plane. Very often such that the angle change of the mouthpiece is about half the angle change of the suction pipe of the vacuum cleaner. Hereby it becomes possible, as mentioned above, to orient the mouthpiece in the surface plane with only little effort due to the exchange in the flexible joint. However, in case a more drastic angle change is imposed on the known mouthpiece, an undesired leak will occur between the suction sole and the supporting surface which is vacuum-cleaned.
An example of such known mouthpiece is described in W084/03429.
It is a drawback of the known mouthpieces that the forward and backward movements to be performed by the vacuum cleaner operator often entail a hunched and thus inconvenient work posture which strains the back of the operator.